Reading the green tea leaves

Green tea is an extremely popular beverage worldwide. Derivatives of green tea, particularly (-)-epigallocatechin-3-gallate (EGCG), have been proposed to have anticarcinogenic properties based on preclinical, observational, and clinical trial data.

In the production of black tea, the plant leaves are picked and then allowed to wither indoors, ferment, and oxidize. For green tea, the plant leaves are steamed and parched after picking to prevent oxidation of the catechins present in the leaf. Oolong tea is produced by "semifermenting" the green leaves, resulting in a tea that is chemically a mixture of green and black teas.

Even though each of these nonherbal teas is derived from C sinensis, qualitative and quantitative chemical differences result from the different processing techniques. For example, black tea contains more complex antioxidants called theaflavins and thearubigins, while steamed and parched green tea contains more of the chemically simpler antioxidants called catechins. Green tea extracts have been used in traditional Chinese medicine for centuries to treat and prevent chronic disease, but conventional medicine practitioners have only recently begun to explore the health-promoting benefits of green tea derivatives

EGCG functions as an antioxidant, preventing oxidative damage in healthy cells, but also as an antiangiogenic agent, preventing tumors from developing a blood supply needed to grow larger. Furthermore, EGCG may stimulate apoptosis in cancerous cells by negatively regulating the cell cycle to prevent continued division. Finally, EGCG exhibits antibacterial activity, which may be implicated in the prevention of gastric cancer.

Enjoy at least 3 cups of organic green tea daily

References:

McKay DL; Blumberg JB The role of tea in human health: an update. J Am Coll Nutr. 2002; 21: 1-13